Governor Schwarzenegger, in one of his last acts as California’s chief executive, has revoked the parole granted a Costa Mesa dentist who killed three patients.

Tony Protopappas was a very bad dentist. In the early 1980s, three of his patients – including a 9-year-old girl – died when Protopappas overdosed them accidentally with anesthesia or other medications.

The Costa Mesa dentist says he was a drinker and a drug addict at the time – and that his substance abuse factored into what happened. A jury convicted Protopappas of second-degree murder; a judge sentenced him to 15 years to life.

Last summer, the state parole board OK’d his release. He’d been in prison for more than 25 years – and he’s sober now. But Governor Schwarzenegger, who leaves office next week, has reversed the board’s decision, noting that the 65-year-old Protopappas “poses a risk of recidivism and violence” if he remains free.